The cementitious stuff being brittle will fragment when flexed by the weight of people. Is this OK?
Since Linoleum is not brittle or inflexible, I'd put shims underneath the plywood if that area is accessible.
Glueing shoebox cardboard on top of the plywood and sanding flat and level may also work but you should topcoat the cardboard with some waterproofing, like polyurethane/varnish/old paint, then whatever Linoleum needs to have, to bond to.
Leveling within 1/16" is close enough, right?